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A Eiras

Publications and source records attributed to A Eiras.

At least 19 recordsLinked to original sources
PubMed2006

Multicenter evaluation of a new 4th generation HIV screening assay Elecsys HIV combi.

Fourth-generation screening assays which permit a simultaneous detection of human immunodeficiency virus (HIV) antigen and antibody reduce the diagnostic window on average by four days in comparison to third-generation antibody assays. Recently, the new automated Elecsys HIV combi was compared in a multicenter study to alternative fourth- and third-generation assays, p24 antigen test and HIV-1 RNA RT-PCR. A total of 104 serocon-version panels, samples of the acute phase of infection after seroconversion (n = 33), anti-HIV-1 positive specimens (n = 572) from patients in different stages of the disease, 535 subtyped samples from different geographical locations, including group M (subtypes A-J) and group O, anti-HIV-2 positive sera (n = 364), dilutions of cell culture supernatants (n = 60) infected with different HIV-1 subtypes, selected performance panels, 8406 unselected samples from blood donors originating from different blood transfusion centers, 3810 unselected sera from daily routine and from hospitalized patients, 9927 unselected samples from South Africa and 1943 potentially interfering samples were tested with the Elecsys HIV combi. Elecsys HIV combi showed a comparable sensitivity to HIV-1 Ag stand-alone assays for early detection of HIV infection in seroconversion panels. The mean time delay of Elecsys HIV combi (last negative sample + 1 day) in comparison to HIV-1 RT-PCR for 92 panels tested with both methods was 3.23 days. The diagnostic window was reduced with Elecsys HIV combi between 1.56 and 5.32 days in comparison to third-generation assays. The specificity of Elecsys HIV combi in blood donors was 99.80% after repeated testing. Our results show that a fourth-generation assay with improved specificity and sensitivity like the Elecsys HIV combi is suitable for blood donor screening due to its low number of false positives and since it detects HIV p24 antigen with a comparable sensitivity to single antigen assays.

Early Diagnosis↗
PubMed2001

Prevalence of and risk factors for IgE sensitization to Anisakis simplex in a Spanish population.

BACKGROUND: The number of allergic reactions to A. simplex reported in Spain has increased dramatically in the last decade. Nevertheless, there have been no studies of the prevalence of and possible risk factors for IgE sensitization to this parasite, possibly because suitably specific diagnostic methods have only recently become available. The objective was to investigate the prevalence of and risk factors for IgE sensitization to A. simplex in Galicia, a region of northwestern Spain with a population of about 3 million and high average fish consumption (78.5 g/person per day). METHODS: The study was performed with a random sample of 2801 healthy blood donors distributed in 53 geographic areas, proportional to the density of donors. IgE sensitization to A. simplex was tested by a capture ELISA method that has proved to be the most specific method currently available. RESULTS: The results showed a total of only 12 positive subjects, of whom five also showed IgG1 sensitization. All positive subjects and 101 randomly selected seronegative subjects were then included in a case-control study of risk factors for sensitization to A. simplex, based on a telephone interview about fish consumption (especially raw and undercooked fish). All seropositive subjects (but only 25% of seronegative subjects) reported consumption of undercooked fish or homemade raw-fish products. CONCLUSIONS: Our results strongly suggest that sensitization to A. simplex is caused only by live larvae, and not by allergens contained in fish tissues, and that ingestion of homemade boquerones (anchovies [Engraulis encrasicholus] in vinegar), and to a much lesser extent of undercooked fish, are the main risk factors for IgE sensitization to Anisakis in this region.

Adolescent↗
PubMed1999

[Properties of stored platelet concentrates: effect of the suspension media and type of pouch used].

PURPOSE: We have evaluated in vitro the effects of using plasma (group A) or PAS-2 (group B) in storing platelets, regarding as well the type of container (conventional polyolefin--PL732--or new oxygen permeable platelet containers--PL2410, Compoflex--), on the metabolism of platelet concentrates--PC--from pools of five buffy coats. MATERIAL AND METHODS: 87, A and B pools of PCs collected in two types of bags were studied. The samples were taken on days 2, 5 and 7, and cell counts, pH, glucose, platelet activation (% CD62) and aggregation response were measured. RESULTS: In group A, when we compared the two types of bags, we observed a difference (p < 0.01) in values of pH and glucose on day 5. These values were more advantageous in new oxygen permeable platelet containers. The rest of the parameters analysed didn't show significant differences. When we compared the PL-2410 containers from groups A and B, we found a lower level of glucose (p < 0.01) in group B, although the levels of glucose in this group on days 5 and 7 of storage were sufficient to support the platelet metabolism. CONCLUSIONS: The use of new oxygen permeable polyolefin containers and additive solutions, PAS-2, allows us to obtain pools of PC with suitable metabolic parameters during storage.

Adult↗
PubMed1998

Reduction of the diagnostic window with a new combined p24 antigen and human immunodeficiency virus antibody screening assay.

In order to reduce the window phase between time of human immunodeficiency virus (HIV) infection and laboratory diagnosis, new fourth generation screening assays which permit a simultaneous detection of HIV antigen and antibody have been developed. In a multicenter study, a new automated fourth generation assay, Enzymun-Test HIV Combi (Boehringer Mannheim GmbH) was compared to third generation assay, p24 antigen tests and Western blot. A total of 37 seroconversion panels, samples of the early infection (n = 42), HIV-1 antibody positive sera, including subtypes A E, and O (n = 1118), HIV-2 positive samples (n = 252) and cell culture supernatants infected with different HIV-1 subtypes and HIV-2 (n = 50), blood donors (n = 6649), hospitalized patients (n = 475), HIV neg. sera with indeterminate Western blot (n = 32), potentially cross reactive serum samples (n = 435) and HIV negative specimens from Cameroon (n = 68) were tested. A total of 16 of 29 seroconversions were detected on average 8.5 days earlier with Enzymun-Test HIV Combi than HIV-1/HIV-2 3rd generation EIA (Abbott Laboratories). Overall, in the 29 panels investigated comparatively with the two assays, the mean time delay between Enzymun-Test HIV Combi and HIV-1/HIV-2 3rd generation EIA was 4.7 days. HIV antigen was detected in three out of 35 seroconversions one bleed earlier with HIV-1 Ag Monoclonal than with Enzymun-Test HIV Combi. Enzymun-Test HIV Combi showed a sensitivity of 100% for HIV antibody detection for HIV-1 group M and O and HIV-2 positive specimens. While p24 antigen of different HIV-1 subtypes was detected with Enzymun-Test HIV Combi in all the 49 cell culture supernatants, HIV Ag was not detected in an HIV-2 virus lysate. A total of 66 false positive results out of 7659 HIV negative samples were obtained with the Enzymun-Test HIV Combi. The specificity for unselected blood donors was 99.6%. The Enzymun-Test HIV Combi permits an earlier diagnosis of HIV infection than third generation assays through the detection of p24 antigen, which may be present in serum samples from individuals with recent HIV infection prior to seroconversion and it shows an excellent sensitivity for antibodies to all known HIV-1 subtypes and HIV-2. The specificity in blood donors and hospitalized patients is comparable to that of other assays.

HIV Antibodies↗
PubMed1995

Pretreatment with oleic acid accelerates the entrance into the mitotic cycle of EGF-stimulated fibroblasts.

We have previously demonstrated that pretreatment of several cell lines with cis-unsaturated fatty acids, like oleic acid, blocks epidermal growth factor (EGF)-induced early ionic signals, and in particular the [Ca2+]i rise. In the present work we show that this blockade does not alter EGF-stimulated cellular proliferation evaluated by direct cell counting, but induces a powerful enhancement in the pulsed thymidine incorporation assay. The lack of effect of oleic acid on EGF-stimulated cellular proliferation was confirmed by repeated cell counts, cumulative thymidine incorporation, and protein synthesis, but a clear synergistic effect between oleic acid and EGF was again obtained by means of time course experiments with pulsed thymidine. Combined flow cytometry analysis and cell counts at earlier times in EGF-stimulated cells showed that oleic acids accelerates the entrance of cells into the replicative cycle leading to an earlier cell division. Afterward, these oleic acid-pretreated cells became delayed by an unknown compensatory mechanism in such a way that at 48 h post-EGF, the cell count in control and oleic acid-pretreated cells was equal. In conclusion (a) oleic acid accelerates or enhances the EGF mitogenic action and (b) in the long term cells compensate the initial perturbation with respect to untreated cells. As a side observation, the widely employed pulsed thymidine incorporation method as a measure of cell division could be extremely misleading unless experimental conditions are well controlled.

3T3 Cells↗
PubMed1995

Highly specific confirmatory western blot test for African swine fever virus antibody detection using the recombinant virus protein p54.

A Western blot technique using a recombinant protein has been developed to confirm positive results obtained in African swine fever (ASF)-specific antibody detection by ELISA. The new confirmatory Western blot is based on the use of protein p54, one of the most antigenic ASF virus structural proteins, expressed in Escherichia coli fused to the N-terminus of MS2 polymerase. The recombinant Western blot assay was highly specific and equally sensitive for ASF virus-infected pigs detection as the conventional Western blot, which uses virus-induced proteins ranging in molecular weight between 23 and 35 kDa. The novel Western blot assay provides a simpler interpretation of the test, eliminates the possibility of false-positive reactions produced by cellular compounds that contaminate the antigen employed in the conventional technique, and avoids the use of live virus in antigen production.

African Swine Fever↗
PubMed1995

Interference between Neisseria meningitidis and PC-KLH induced anti-phosphorylcholine PFC responses in NZB/W autoimmune mice.

In this work, we demonstrate that the simultaneous injection of PC-KLH and Neisseria meningitidis-derived antigens [NMB or PC-(NMB)HI] induced in old NZB/W mice defective responses as does PC-KLH challenge. On the other hand, the simultaneous injection of both immunogenic preparations of N. meningitidis evoked responses similar to those shown by old mice challenged with NMB alone. Alteration in PC-specific PFC responses also affected hapten-free inhibition profiles and their heterogeneities. The increase in PC50s of anti-phosphorylcholine PFC responses and their heterogeneities induced by certain antigens with aging is correlated with a decrease in T15 idiotype expression, suggesting that after the T15 dominant clone disappears no other clone takes control of the anti-PC response. These results suggest that the mechanism(s) involved in the regulation of T15 marker expression play an important role in the inability of old NZB/W mice to mount good anti-PC responses and suggest that regulatory mechanisms induced by PC-KLH dominate those elicited by NMB.

Aging↗
PubMed1994

Characterization and molecular basis of heterogeneity of the African swine fever virus envelope protein p54.

It has been reported that the propagation of African swine fever virus (ASFV) in cell culture generates viral subpopulations differing in protein p54 (C. Alcaraz, A. Brun, F. Ruiz-Gonzalvo, and J. M. Escribano, Virus Res. 23:173-182, 1992). A recombinant bacteriophage expressing a 328-bp fragment of the p54 gene was selected in a lambda phage expression library of ASFV genomic fragments by immunoscreening with antibodies against p54 protein. The sequence of this recombinant phage allowed the location of the p54 gene in the EcoRI E fragment of the ASFV genome. Nucleotide sequence obtained from this fragment revealed an open reading frame encoding a protein of 183 amino acids with a calculated molecular weight of 19,861. This protein contains a transmembrane domain and a Gly-Gly-X motif, a recognition sequence for protein processing of several ASFV structural proteins. In addition, two direct tandem repetitions were also found within this open reading frame. Further characterization of the transcription and gene product revealed that the p54 gene is translated from a late mRNA and the protein is incorporated to the external membrane of the virus particle. A comparison of the nucleotide sequence of the p54 gene carried by two virulent ASFV strains (E70 and E75) with that obtained from virus Ba71V showed 100% similarity. However, when p54 genes from viral clones generated by cell culture passage and coding for p54 proteins with different electrophoretic mobility were sequenced, they showed changes in the number of copies of a 12-nucleotide sequence repeat. These changes produce alterations in the number of copies of the amino acid sequence Pro-Ala-Ala-Ala present in p54, resulting in stepwise modifications in the molecular weight of the protein. These duplications and deletions of a tandem repeat sequence array within a protein coding region constitute a novel mechanism of genetic diversification in ASFV.

African Swine Fever Virus↗
PubMed1993

Comparison of the protective efficacy of Aujeszky's disease (pseudorabies) virus glycoproteins obtained from different sources.

The immunogenic properties of a series of glycoprotein preparations are compared using inactivated conventional vaccines as reference. Serological response and protective efficacy of vaccination of mice and pigs are evaluated for glycoprotein immunogens obtained from various sources. BHK-21 cell cultures were infected with Aujeszky's disease virus and used as antigenic source. Glycoproteins were obtained from (i) the whole culture (ii) the cell sediment and (iii) the clarified supernatant. Both in pigs and in mice, protection was greater with glycoproteins purified from infected-cell membranes than with viral mature particle glycoproteins. The specific profiles of humoral responses were basically identical regardless of the source of glycoprotein. Bartha strain, one of the gI- strains most commonly used as an attenuated vaccine, was also used as a glycoprotein source. Immunogens obtained from this strain were protective in challenge trials with the virulent E-974 strain of the Aujeszky's disease virus. Glycoproteins did not induce detectable delayed type hypersensitivity in mice but conferred greater protection than particulate antigens (which, conversely, did induce a detectable delayed type hypersensitivity reaction). Until the recent proposal of the potency criterion delta 7, no objective method was available to evaluate the degree of protection conferred by Aujeszky's disease vaccines. In this study, we thus used the protection index, a quantitative parameter designed to evaluate potency of vaccines against Aujeszky's disease virus.

Animals↗
PubMed1993

Efficacy of various non-oily adjuvants in immunization against the Aujeszky's disease (pseudorabies) virus.

Standard oil and various non-oily adjuvants were compared for use in immunization against the Aujeszky's disease (pseudorabies) virus, both in mice and swine, and using either inactivated virions or purified glycoproteins as antigen. Mineral oil, sodium alginate, aluminium hydroxide, and saponin were assayed in mice as adjuvants for inactivated virions, saponin being the most efficient. The addition of Mab anti-CD3 did not improve either immune response or protection achieved in mice using viral particles with oil or sodium alginate. When purified glycoproteins were used as antigens, the use of ISCOM greatly enhanced specific T-cell responses and protection of mice. The incorporation of Mab anti-CD3 into ISCOM conferred 100% protection of mice. Surprisingly, when an ISCOM containing glycoproteins was assayed in swine in a single-dose trial, no improvement on the protection conferred by the oily adjuvant was observed.

Adjuvants, Immunologic↗
PubMed1992

Antigens involved in vaccination of swine against Aujeszky's disease (pseudorabies) virus.

The polypeptide and glycopolypeptide composition of a local virulent Aujeszky's disease virus (suid herpesvirus 1, SHV-1) strain (E-974) was determined in order to characterize the individual SHV-1 antigens inducing the serological responses in immunized and non-immunized animals. A commercially available inactivated vaccine of known efficacy and three experimental immunogen preparations (whole inactivated SHV-1 particles, lectin-purified glycoproteins from SHV-1 culture, and a combination of both) were used for immunization. Sera of two-month old immunized and non-immunized animals were analyzed by ELISA, seroneutralization and Western immunoblotting prior to and following challenge with E-974. Sera of 7- to 30-day-old piglets littered by immunized and non-immunized sows were likewise analyzed by immunoblotting. The following variables were determined: the total level of anti-SHV-1 antibodies, the level of neutralizing antibodies, the IgG responses to individual SHV-1 antigens, and the clinical parameters and degree of protection of the animals. The whole-particle experimental immunogen conferred greatest protection, but correlation between antibody levels and the degree of protection was imperfect. Serological responses seemed to be directed against certain structural polypeptides and viral envelope glycoproteins. The glycoprotein immunogen caused a selective response to bands which closely resemble the glycopolypeptides gII and gIII. A 71 kDa component of uncertain location within the viral structure appeared to be one of the main antigens involved in porcine serological response to SHV-1 and colostral protection of piglets.

Animals↗
PubMed1987

Immunoresponses to Neisseria meningitidis epitopes: immunomodulation by meningococcus B acts on more than one meningococcal surface epitope.

Neisseria meningitidis group B strain M986 (serotypes 2a, 7) (NMB) elicits a specific primary antiphosphorylcholine immune response in mice but not a secondary response. The ability of other serotype and serogroup meningococci to induce similar primary responses in mice was studied, as was the immunogenicity of trinitrophenyl coupled NMB (TNP-NMB) in primary and secondary antitrinitrophenyl responses. Except for NMB, all other strains tested (three serogroup B and one serogroup A meningococcal strains) were found to be very poor phosphorylcholine immunogens. TNP-NMB, however, though proving to be a very good TNP antigen, was only a weak phosphorylcholine antigen. Priming NBF1 female mice with TNP-NMB one month or more before challenging them with the same antigen induced a strong depression of anti-TNP response in the subsequent challenge. However, this effect was not observed with Xid NBF1 male mice. Furthermore, priming mice with NMB weakly affected the anti-TNP response, but greatly depressed the antiphosphorylcholine response, after TNP-NMB challenge. In addition, whereas apparently only one TNP-specific B cell subpopulation was responding in unprimed mice challenged simultaneously with TNP-NMB and TNP-Ficoll (non-additive response), priming mice with NMB appeared to facilitate the independent activation of two different TNP-specific B cell subpopulations (additive response).

Animals↗
PubMed1987

Immunoresponses to Neisseria meningitidis epitopes: in vivo analysis of immunocompetent cells involved in suppression of secondary response to phosphorylcholine.

The immune response to phosphorylcholine (PC) antigens has been extensively studied in recent years. Neisseria meningitidis serogroup B M986 (NMB) was recently reported to induce a PC-specific plaque-forming cell (PFC) immuno-response in mice, a characteristic useful for the study of immunomodulating properties of N. meningitidis. With this technique, priming mice with low doses of NMB has been shown greatly to impair their ability, one month after priming, to mount an anti-PC response induced by NMB; this suppression is permanent, does not involve switching from IgM to another immunoglobulin class, transiently affects the T15 idiotype expression and is carrier specific. We report, based on an analysis of spleen cells from NMB-primed mice in an adoptive transfer model, that this suppression does not appear to be mediated by B lymphocytes nor does it seem to be under the direct control of T lymphocytes; rather, it involves radio-resistant cells. Additionally, our results show that NMB modulates the idiotype composition of the anti-phosphorylcholine response, probably by enhancing the expression of so called hapten-augmentable PFC. These results demonstrate that NMB can interfere effectively with the immune response in a variety of ways.

Animals↗
PubMed1987

[Anti-phosphorylcholine response of autoimmune NZB/W mice: variations with age of serum titers and homogeneity].

Antibody titers and avidity of sera of autoimmune NZB/W mice in responses induced by different antigens were determined. Results show an age-dependent decrease of the antibody titer in sera from female mice immunized with phosphorylcholine coupled to keyhole limpet haemocyanin. This decrease was not detected when using as immunogen an antigenic preparation of Neisseria meningitidis that naturally induces anti-phosphorylcholine antibodies, but was detected with a modification of this antigen (heat inactivation and further coupling with the hapten). Determinations of inhibition profiles of antisera suggest that this loss of immune competence is paralleled by a decrease in avidity and homogeneity of antisera. This finding may be related to the loss of idiotypic clonal dominance recently reported to occur in these mice.

Aging↗
PubMed1986

Immunoresponses to Neisseria meningitidis epitopes: suppression of secondary response to phosphorylcholine is carrier specific.

Results of our previous work have shown that Neisseria meningitidis serogroup B M986 can induce a phosphorylcholine (PC)-specific plaque-forming cell immunoresponse in mice. Also, a single injection of a relatively low dose of meningococci in NBF1 female mice induced a priming time-dependent suppression on subsequent meningococcus challenge. This suppression was not due to switching to another class of immunoglobulin nor to the presence of a capsule on N. meningitidis. In this study we show that suppression induced by meningococcus is carrier specific. Furthermore, we offer evidence suggesting that the structure(s) on meningococcus that trigger this suppression is heat labile and different from the antigenic structure(s) recognized by the suppressed B cells. In addition, we found that there is a gradual increase in antibody secretion rates of N. meningitidis-induced anti-PC plaque-forming cells that correlates with N. meningitidis priming time. Rather unexpected was the fact that pretreatment of mice with PC-keyhole limpet hemocyanin (thymus-dependent antigen) had a great influence on the subsequent PC-specific immunoresponses induced by N. meningitidis and PC-coupled heat-inactivated meningococcus [PC-(NMB)HI], as shown by (i) a striking decrease in T15 idiotype expression, (ii) concomitant direct anti-PC plaque-forming cells reduction, (iii) switching to immunoglobulin G (N. meningitidis-induced immunoresponse) or immunoglobulin G plus immunoglobulin A [PC-(NMB)HI-induced immunoresponse], and (iv) a significant increase in heterogeneity of plaque-forming cell secretion rates. The possibility that N. meningitidis, PC-(NMB)HI, and PC-KLH stimulate B lymphocytes pertaining to three different subpopulations embedded in distinct regulatory circuits is discussed, with emphasis on the interrelationships between T-dependent and T-independent lymphocyte compartments. We focus on the possibility of the existence of high-level regulatory circuits in which lymphocyte subpopulations or sets of lymphocyte subpopulations with different requirements of activation are connected.

Animals↗